Sensors made of high-temperature resistant piezoelectric materials are widely used to test a series of in situ working data of the tested system under high temperatures (400° C.˜1600° C.). Being first-hand data obtained in situ, these data provide a more comprehensive, reliable and accurate grasp on the working status of the whole system. For example, high-temperature pressure sensors made with lanthanum gallium silicate crystal (langasite) can be used to monitor the internal pressure of the engine cylinders in engines for spacecraft, aircraft, and automobiles, etc. The engine cylinder pressure monitored in real time can provide important engine operating parameters. These parameters can not only be used to analyze whether the engine is under normal operation, but also detect the engine cylinder combustion. By analyzing the data collected by the sensor, the life of the engine can be extended and the combustion efficiency of the fuel in the cylinder can be improved. Therefore, the development of such sensors is vital to the national economy and other areas. At present, this type of sensor has been used in engines for spacecraft, aircraft, and automobiles, and been extensively used in the study of the engines, in some countries.
However, the properties of materials are different under a high temperature and under a normal temperature, in other words, the properties of materials vary with temperature. For example, some materials that are insulators under normal temperatures may become conductors under a high temperature. Therefore, in order to use high-temperature materials in a high temperature environment, the properties of such materials under high temperatures shall be detected at first, namely determining the variation with temperature of some property of such a material, especially the variation with temperature under high temperatures (400° C.˜1600° C.).
Conventional testing of material properties is a regular testing generally carried out at a lower temperature (<400° C.). In order to test the properties of material at a high temperature, it is necessary to introduce a test system capable of operating at a high temperature. However, the test instruments are readymade in this test system, lacking a fixture for placing a sample at a high temperature. Although there are reports on testing the material properties at a high temperature in some countries, none provide relevant information on corresponding fixtures. In China, applications in the high-temperature field have just begun. Lack of a fixture for testing the property of a material at a high temperature directly led to the rarity of information on high-temperature property testing.
Testing of high-temperature properties of materials usually needs to go through a process of heating—testing—cooling, while the period for heating and cooling usually takes up more than 80% of the whole testing period, resulting in a low efficiency of the test. Accordingly, there is an urgent need in the art for a fixture that can improve the efficiency of the test.